1. Field of the Invention
This invention relates to an electromagnetic agitating method in a mold for continuously casting a steel slab.
2. Description of the Prior Art
A continuous casting of a slab is carried out by a method wherein molten steel poured into a mold from a tundish through an immersed nozzle is cooled from its surrounding part by a wall of the mold and then a solidified shell is pulled while forming and growing in the mold. In this case, as shown in FIG. 10, the molten steel fed from the tundish (not shown) into the mold flows out through a discharging hole 16 of the immersed nozzle 15, the molten steel stream 17 may strike against a narrow surface part 18 of the mold M to generate a descending flow 19 and then this descending flow 19 may deeply immerse into a slab S as a major flow of the molten steel flow.
According to this type of continuous casting method, it is already known that some obstacles or bubbles such as argon gas enclosed in the descending flow 19 are caught at the interface of the consolidated shell to form an accumulated obstacle band which will be exposed as defects during a rolling operation.
In recent years, in order to improve such a problem as above, there is provided a continuous casting method in which an electromagnetic agitating operation is applied.
For example, Jap. Pat. Laid-Open No. Sho 60-37251 describes a method for improving the quality of a casted piece by a method wherein two electromagnetic agitating devices are separately arranged within a wide surface of the mold at right and left sides, and agitating force directions of the separated electromagnetic agitating devices are changed over for their operation.